Field of the Invention
One or more embodiments of the present invention relate to a composite cathode active material, and a cathode and a lithium battery each including the composite cathode active material, and a method of preparing the composite cathode active material.
Description of the Related Art
In general, transition metal compounds such as LiNiO2, LiCoO2, LiMn2O4, LiFePO4, LiNixCo1-xO2 (0≤x≤1), and LiNi1-x-yCoxMnyO2 (0≤x≤0.5, 0≤y≤0.5), and lithium oxides thereof are currently used as cathode active materials for lithium batteries. Batteries made from these cathode active materials have limited electrical capacities, and thus, novel cathode active materials having various structures have been suggested. In particular, along with the trend for high-capacity batteries, composite oxides are suggested as an alternative to transition metal-based compounds.
An example of the composite oxides having a layered structure is xLi2MO3-(1-x)LiMeO2 (where 0<x<1, and M and Me are transition metals). Although this composite oxide has a high theoretical electrical capacity, it may practically have a low electrical conductivity since Li2MO3 is a non-conductor, and thus leads to reduced lifetime characteristics' and high-rate characteristics.
Therefore, there still is a need in the art for a cathode active material having high capacity and improved lifetime and high-rate characteristics.